Video systems are widely used in the field of surveillance of buildings, traffic, private homes, supermarkets and the like. For some applications it is useful to save the video information for a later access or analysis. As the saved data volume increases with the number of video cameras of a video system and the recorded time there is a need for video databases, which allow a fast searching for relevant video information.
Document WO 00/45338 discloses a system and method for representing trajectories of moving objects for content-based indexing and retrieval of visual animated data. The system allows identifying a selected object in a sequence of visual animated data frames and determining a trajectory of the selected object in a two dimensional or three dimensional coordinate space. In a next step high-level descriptors, which represent the trajectory of the object are created and merged with the original sequence of visual animated data thereby creating a “new signal”. The new signal may be searched by matching the trajectory information stored in the descriptor with trajectory describing criteria selected for example by a user.
Document WO 2005/050971 A2 discloses a video surveillance system using virtual tripwires of arbitrary shape. The video surveillance system comprises a sensing device like a video camera and a computer system. The tripwires are drawn by a user on a video image captured by the video camera and trigger in case a tripwire rule is fulfilled a specific reaction of the video surveillance system. The video data captured by the video camera can be processed on-line or off-line. In all cases the tripwire-rules are applied on the video data.